Attempts to use resins as materials for precision molded articles have been increasingly made. However, since resins generally have a high linear expansion coefficient, they are apt to undergo dimensional change owing to change in environmental temperatures and furthermore, when molded into articles of thick wall, considerable shrinkage occurs, and thus, they have many problems as materials for precision molded articles.
Recently, thermoplastic norbornene resins excellent in heat resistance and moisture resistance have been noticed as molding materials in various fields. Thermoplastic norbornene resins can be precision molded and are superior in dimensional stability against change of humidity, but like other resins, have a high linear expansion coefficient. Therefore, they have problems in dimensional stability against temperature change and cannot be used as materials for precision molded articles used in an environment where temperatures are apt to change. Furthermore, even if precision molding is possible, shrink marks have sometimes been formed.
In order to decrease linear expansion coefficient and inhibit formation of shrink marks, it has been attempted to add inorganic fillers to thermoplastic norbornene resins, but when inorganic fillers are added, there are problems that flowability decreases to cause deterioration in moldability and furthermore, transferability of mold configuration to the surface of molded articles deteriorates and smoothness of the surface of the molded articles lowers.